The mooring buoys known to persons skilled in the art are subject to substantial dangers caused by the motions of ships. Collisions frequently happen and lead to loss of the entire buoy, with expensive apparatus thereon. Also and most seriously such collisions jeopardize parts of the colliding ship such as the rudder or propeller or both. These difficulties are encountered mainly in narrow waters, and even when collisions are avoided the maneuvering of ships is frequently impaired by mooring buoys.